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| author | Nayna Jain <nayna@linux.ibm.com> | 2018-10-09 23:00:34 +0530 |
|---|---|---|
| committer | Mimi Zohar <zohar@linux.ibm.com> | 2018-12-11 07:10:33 -0500 |
| commit | b5ca117365d960fe5e4fe272bcc8142c28769383 (patch) | |
| tree | 6e306a5c52ad13271a2d947c9a41922f1ddf709d /security | |
| parent | 0914ade209c452cff6a29b1c0ae6fff3167fa1d0 (diff) | |
| download | linux-b5ca117365d960fe5e4fe272bcc8142c28769383.tar.gz linux-b5ca117365d960fe5e4fe272bcc8142c28769383.tar.bz2 linux-b5ca117365d960fe5e4fe272bcc8142c28769383.zip | |
ima: prevent kexec_load syscall based on runtime secureboot flag
When CONFIG_KEXEC_VERIFY_SIG is enabled, the kexec_file_load syscall
requires the kexec'd kernel image to be signed. Distros are concerned
about totally disabling the kexec_load syscall. As a compromise, the
kexec_load syscall will only be disabled when CONFIG_KEXEC_VERIFY_SIG
is configured and the system is booted with secureboot enabled.
This patch disables the kexec_load syscall only for systems booted with
secureboot enabled.
[zohar@linux.ibm.com: add missing mesage on kexec_load failure]
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Diffstat (limited to 'security')
| -rw-r--r-- | security/integrity/ima/ima_main.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 1b88d58e1325..df0b2ee49fa2 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -505,20 +505,26 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, */ int ima_load_data(enum kernel_load_data_id id) { - bool sig_enforce; + bool ima_enforce, sig_enforce; - if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE) - return 0; + ima_enforce = + (ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE; switch (id) { case LOADING_KEXEC_IMAGE: - if (ima_appraise & IMA_APPRAISE_KEXEC) { + if (IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) + && arch_ima_get_secureboot()) { + pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n"); + return -EACCES; + } + + if (ima_enforce && (ima_appraise & IMA_APPRAISE_KEXEC)) { pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } break; case LOADING_FIRMWARE: - if (ima_appraise & IMA_APPRAISE_FIRMWARE) { + if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) { pr_err("Prevent firmware sysfs fallback loading.\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } @@ -526,7 +532,8 @@ int ima_load_data(enum kernel_load_data_id id) case LOADING_MODULE: sig_enforce = is_module_sig_enforced(); - if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES)) { + if (ima_enforce && (!sig_enforce + && (ima_appraise & IMA_APPRAISE_MODULES))) { pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } |